Direct lighting is lighting provided from a source without reflection from other surfaces. In electrical lighting, direct lighting usually describes an installation of ceiling mounted or suspended luminaires with mostly downward light distribution characteristics. Direct lighting creates glare and harsh shadows. Parabolic fixtures create shafts of intense light. These shafts result in uneven illumination, harsh glare, and hard shadows. Deep wall shadows can cause eye strain and affect well-being and productivity.
Expensive “VDT-type” (visual display terminal) parabolic fixtures further restrict the lateral distribution of light, keeping glare off of some VDT's while increasing shadows, undue contrast and direct glare. Further, direct lighting causes veiling reflection and hard shadows.
Lensed troffers and wraps are often used for budget purposes, but result in too much glare for many uses. For example, these lighting types do not meet ANSI recommendations for today's classrooms. Light between 55° and 90° from lensed troffers and wrap-style type lighting goes directly onto computer screens and causes reflective glare.
Most indirect lighting devices require at least a 15″ spacing between the ceiling and the top of the fixture. Due to the need for this 15″ spacing, the aesthetics of the lighting fixture, in low-ceiling applications, are objectionable to architects. In addition there is concern that the low-hanging indirect devices will be vandalized in schools. Further, building codes require that the bottom of the fixtures be at least 6′–8″ AFF. Due to these restrictions and limitations, indirect fixtures are not generally used in spaces with the typical 8′–0″ to 8′–6″ ceiling heights.